4. Precision Fertigation Project

The HAL funded (AP12006) three year APAL PIPS “Precision Fertigation for Improved Apple Orchard Productivity” project commenced in October 2012. This collaborative project with Department of Primary Industries, Victoria (DPI VIC) and Plant and Food Research New Zealand (PFR NZ) aims to determine the influence of nutrient and water use efficiency on apple trees through fertigation to facilitate the consistent production of high quality fruit. 

This project will:  investigate the effect of water stress and water surplus on Nitrogen (N) uptake; investigate the effect of N and Potassium (K) fertigation treatments on tree and fruit nutrition; investigate the influence of fertigation on N storage and remobilisation, investigate the influence of application type, soil type and rainfall on N leaching and undertake preliminary investigations of remote sensing of N deficiencies using Canopy Chlorophyll Content Index (CCCI) capability from remote sensing. Overall, this project will facilitate the development of fertigation guidelines for growers to optimise whole tree nutrition and fertiliser management in order to increase orchard productivity and sustainability.

In a Royal Gala orchard on M26 rootstock in the Huon Valley Tasmania, irrigation treatments (60, 100 and 160% of grower irrigation practise) and fertigation infrastructure were installed to implement five N treatments, including a zero N control in a randomised split block experimental design, replicated four times. Pre harvest treatments commenced in November 2012, and post harvest treatments were applied in late March 2013 and will continue at these times throughout the life of the project.

Drainage fluxmeters (DFMs), soil moisture probes and sap flow sensors were installed in October 2012 by scientists and technicians from Tasmanian Institute of Agriculture (TIA) and PFR NZ in the same orchard to monitor N fluxes and water movement. Instrumentation was connected to data loggers for continuous logging of drainage occurrence and volume, soil water content and tree transpiration. Measurements of tree N status in leaf petioles will be collected at three intervals during the growing season and in one-year old wood during winter dormancy.  Tree size (trunk diameter) will be measured each winter. Fruit was harvested in March and yield and fruit quality assessments of size, weight, TSS, firmness were measured in the laboratory.

Data will be used in combination with data collected from orchards in the Goulburn Valley (DPI VIC) to investigate the effects of irrigation deficit and surplus on tree nitrogen status, and to validate a model (undertaken by PFR NZ) for the prediction of nitrogen use efficiency in apple orchards.